Mechanical Interlocking for Connecting Electrical Wires to Flexible, FDM, 3D-Printed Conductors

BSc assignment

Students: EE, AT

Focus: mainly experimental (but can also be modelling)


Background: For flexible applications like soft robotics and biomedical devices it is difficult to reliably connect electrical contacts. In previous research we studied electrical contacts for flexible 3D-printed conductors that uses mechanical interlocking to achieve reliable connections. The interlocking is created by embedding punctured copper tape during printing, creating interlocking structures between copper and polymer. The used sample design did not allow for perfect measurements of the contact resistance (at best a mix of the contact resistance with some sample resistance components could be determined) and this made it difficult to study the underlying principles.


Goal: Improve fabrication and characterization of electrical contacts with mechanical interlocking to gain more understanding on principles of operation (and/or use modeling to study the principles)


Recommended directions for study:

  • For improved contact resistance measurements the Transfer Length Method (TLM) can be used. By doing this in an oven at different temperatures the effect of thermal expansion on the contact resistance can be measured (e.g. in combination with various hole patterns).
  • Mechanical pulling on contacts can be performed while doing a TLM measurement to study the effect of stress and deformation on the contact resistance.
  • A more reliable method of fixating/placing the electrodes during printing can be studied. Currently the electrodes are fixated by means of touching them with a soldering iron. A jig or rolling wheel could exert pressure and temperature in a more controlled way, improving the repeatability of the fabrication.
  • Modeling can be done to determine the effect of hole patterns, stress distributions, thermal shrinkage and effective contact area on the contact resistance and mechanical properties. This might be quite difficult, however for elastic materials already a lot of knowledge on the effect of pressure on contact resistance and stress distributions in rivet connections is available.